title: Active-resisted stance modulates regional bone mineral density in humans with spinal cord injury.
abstract: OBJECTIVE
  In people with spinal cord injury (SCI), active-resisted stance using electrical stimulation of the quadriceps delivered a therapeutic stress to the femur (∼150% of body weight) and attenuated bone mineral density (BMD) decline. In standard densitometry protocols, BMD is averaged over the entire bone cross-section. An asymmetric adaptation to mechanical load may be masked by non-responding regions. The purpose of this study was to test a novel method to assess regional BMD of the femur in individuals with SCI. We hypothesize that there will be regional bone-sparing changes as a result of active-resisted stance.
  
  
  METHODS
  Mixed cross-sectional and longitudinal.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Twelve individuals with SCI and twelve non-SCI controls.
  
  
  METHODS
  Individuals with SCI experienced active-resisted stance or passive stance for up to 3 years.
  
  
  METHODS
  Peripheral quantitative computed tomography images from were partitioned so that femur anatomic quadrants could be separately analyzed.
  
  
  RESULTS
  Over 1.5 years, the slope of BMD decline over time was slower at all quadrants for the active-resisted stance limbs. At >2 years of training, BMD was significantly higher for the active-resisted stance group than for the passive stance group (P = 0.007). BMD was preferentially spared in the posterior quadrants of the femur with active-resisted stance.
  
  
  CONCLUSIONS
  A regional measurement technique revealed asymmetric femur BMD changes between passive stance and active-resisted stance. Future studies are now underway to better understand other regional changes in BMD after SCI.
authors.affiliation: Department of Physical Therapy & Rdhabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
authors.forename: Shauna
authors.initials: S
authors.lastname: Dudley-Javoroski
authors.forename: Richard K
authors.initials: RK
authors.lastname: Shields
mesh_terms: D000293:Adolescent; D000328:Adult; D015519:Bone Density / Q000502:physiology*; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D026741:Physical Therapy Modalities; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging; D013119:Spinal Cord Injuries / Q000473:pathology / Q000534:rehabilitation*; D014057:Tomography, X-Ray Computed; D055815:Young Adult